Cushing's Disease in Cats: Symptoms, Diagnosis & Treatment (2026)
Quick Facts: Feline Cushing's Disease
- What it is: Excess cortisol production — called hyperadrenocorticism (HAC). Rare in cats, but distinct and treatable.
- Two types: Pituitary-dependent (~80–85%) and adrenal-dependent (~15–20%); iatrogenic (from steroids) is far less common in cats than dogs
- Hallmark sign: Fragile skin that tears with minimal trauma — far more prominent in cats than in dogs
- Concurrent diabetes: ~80% of cats with Cushing's have insulin-resistant diabetes mellitus
- ALP is NOT reliable: Cats lack the corticosteroid-induced ALP isoform — the key bloodwork clue in dogs doesn't apply here
- Key diagnostic test: Low-dose dexamethasone suppression test (LDDS) at 0.1 mg/kg — 10× the dose used in dogs
- Treatment: Trilostane (Vetoryl) for medical management; concurrent diabetes often improves markedly once cortisol is controlled
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Upload My Cat's ResultsCushing's disease is far more common in dogs than cats — but when it does occur in cats, it looks different enough that owners and even vets can be caught off guard. The classic dog picture (very high ALP, pot belly, hair loss, excessive thirst) only partially applies. In cats, the defining feature is often skin that tears with the gentlest handling, combined with a diabetic cat that refuses to respond to insulin. Here's what feline Cushing's actually looks like — and what the workup involves.
What Is Cushing's Disease (Hyperadrenocorticism)?
Cushing's disease — medically called hyperadrenocorticism (HAC) — occurs when the adrenal glands produce too much cortisol. Cortisol is the body's primary stress hormone. In normal physiology, it is carefully regulated: the hypothalamus releases CRH, which triggers the pituitary to release ACTH, which signals the adrenal glands to produce cortisol. When that feedback loop breaks down — because of a tumor at the pituitary or adrenal level — cortisol production runs chronically high.
Sustained excess cortisol affects virtually every organ system: it degrades collagen (causing fragile skin and poor healing), drives insulin resistance (causing diabetes), breaks down muscle, suppresses immune function, and redistributes body fat.
Pituitary-dependent HAC (~80–85% of cases)
A tumor (usually a small adenoma) in the pituitary gland secretes excess ACTH, which continuously over-stimulates both adrenal glands to produce cortisol. Both adrenals become enlarged. This is the most common form in cats, as in dogs. Note: acromegaly is another pituitary tumor condition in cats that also causes insulin-resistant diabetes — but through growth hormone excess rather than ACTH, and requires different treatment.
Adrenal-dependent HAC (~15–20% of cases)
A tumor in one adrenal gland (adenoma or carcinoma) autonomously produces cortisol regardless of ACTH levels. The other adrenal gland shrinks from disuse. Adrenal carcinomas are more common in cats than dogs with this form, and more likely to be locally invasive or metastatic.
Iatrogenic HAC (from exogenous steroids) — rare in cats
Unlike dogs, cats are relatively resistant to exogenous corticosteroids — they require higher doses for longer periods before iatrogenic Cushing's develops. When it does occur (usually from long-term oral or injectable corticosteroids), signs are the same, and treatment is gradual steroid tapering rather than hormone-blocking drugs.
How Feline Cushing's Differs From Canine Cushing's
This distinction matters clinically. Using the dog checklist to screen cats will miss cases and mislead interpretation of results:
| Feature | Cats | Dogs |
|---|---|---|
| Prevalence | Rare | Common |
| Skin fragility | Prominent — skin tears with minimal trauma; major clinical feature | Mild thinning; rarely tears spontaneously |
| Concurrent diabetes | ~80% of cats have insulin-resistant DM | Less common; some dogs develop secondary DM |
| ALP as a marker | Not useful — cats lack the corticosteroid-induced ALP isoform | Very reliable — often 5–10× normal, key screening clue |
| LDDS dose | 0.1 mg/kg — 10× the dog dose | 0.01 mg/kg |
| ACTH stim sensitivity | ~50% — less useful for diagnosis in cats | ~80–85% — primary monitoring tool |
| Iatrogenic from steroids | Rare — cats are relatively steroid-resistant | Common — even short courses can suppress HPA axis |
| Adrenal carcinoma rate | Higher proportion malignant | Mix of adenoma and carcinoma |
Symptoms of Cushing's Disease in Cats
Signs develop gradually and may be attributed to aging or to the concurrent diabetes. The presentation that should most reliably raise suspicion is a diabetic cat requiring unusually high or escalating insulin doses — that pattern of insulin resistance is the most common reason Cushing's is investigated in cats.
Skin fragility syndrome — the most distinctive sign
The skin becomes extremely thin, inelastic, and fragile. It tears with minor trauma — routine scruffing, blood draws from the neck, grooming, or even gentle petting can cause the skin to split open. Wounds may gape rather than hold together and heal very slowly. Owners sometimes notice the skin feels papery or that it tears when their cat squeezes through a tight space. This degree of fragility is not seen in dogs with Cushing's and should be considered a red flag for feline HAC.
Concurrent insulin-resistant diabetes mellitus
Roughly 80% of cats with Cushing's have diabetes mellitus. Often this presents as a cat that was previously well-controlled on insulin but now requires escalating doses, or a newly diagnosed diabetic cat whose glucose cannot be stabilized despite high insulin doses. Cortisol is a potent counter-regulatory hormone that blocks insulin action and drives glucose production — treating the Cushing's often dramatically reduces insulin requirements, and some cats achieve diabetic remission. See our guide to cat diabetes blood sugar monitoring for what stable management looks like when cortisol is controlled.
Other common signs
- •Pendulous pot belly: Fat redistribution to the abdomen combined with muscle wasting creates a rounded, sagging belly even in cats that are not overweight.
- •Bilateral symmetrical hair loss: Thinning along the trunk and flanks; the head and limbs are usually spared. The coat may appear dull and unkempt. Some cats also develop skin hyperpigmentation in affected areas.
- •Muscle wasting and weakness: Loss of temporal muscle mass, weakness in the hindlimbs, reluctance to jump. Cats may appear tucked-up in the hindquarters.
- •Recurrent infections: Skin infections, abscesses, and urinary tract infections — excess cortisol suppresses immune function.
- •Polydipsia and polyuria: Usually from concurrent diabetes rather than cortisol directly (unlike dogs, where cortisol itself causes significant PU/PD by impairing ADH).
- •Neurological signs: If a pituitary macroadenoma is present — circling, disorientation, behavior change, or seizures may appear as the tumor grows.
Suspect Cushing's in Any Diabetic Cat With Poor Insulin Response
Bloodwork Findings in Feline Cushing's
Routine bloodwork can raise suspicion but cannot confirm the diagnosis. The key point: do not rely on ALP — the corticosteroid-induced ALP isoform that makes ALP such a reliable marker in dogs does not exist in cats. A normal ALP does not rule out Cushing's in a cat.
| Test | Finding in Feline HAC | Notes |
|---|---|---|
| Blood glucose | High — often markedly elevated | ~80% of cats have concurrent DM; glucose may be very high if uncontrolled |
| Fructosamine | Elevated | Reflects sustained hyperglycemia over 2–3 weeks; useful for assessing concurrent DM |
| ALP | Often normal or mildly elevated | Not a reliable marker in cats — corticosteroid-induced isoform doesn't exist |
| ALT | Mildly to moderately elevated | Hepatic lipidosis or steroid hepatopathy; less dramatic than in dogs |
| Cholesterol | Often elevated | Cortisol promotes fat mobilization and alters lipid metabolism |
| CBC — leukogram | Stress leukogram | Neutrophilia, lymphopenia, eosinopenia — the classic cortisol-driven white cell pattern |
| Urine specific gravity | Dilute if concurrent DM | Unlike in dogs, cortisol alone rarely causes marked PU/PD in cats without DM |
| Urine glucose | Present if concurrent DM | Glucosuria from the concurrent diabetes, not from Cushing's directly |
ALP in Cats vs. Dogs — A Critical Distinction
Diagnosing Cushing's Disease in Cats
Diagnosis requires specific hormone tests. The approach in cats differs meaningfully from dogs in both the tests chosen and the doses used.
Urine cortisol:creatinine ratio (UCCR) — screening test
A first-morning urine sample collected at home (away from the stress of a vet visit) is submitted for cortisol and creatinine measurement. An elevated UCCR suggests excess cortisol production and warrants further testing. A normal result makes Cushing's unlikely. Because stress itself raises cortisol, samples collected in the clinic may be falsely elevated — home collection is important.
Low-dose dexamethasone suppression test (LDDS) — preferred confirmatory test
Dexamethasone is injected IV or IM, and cortisol levels are measured at 0, 4, and 8 hours. In a normal cat, cortisol suppresses substantially. In Cushing's, it does not. The critical difference from dogs: cats require 0.1 mg/kg — ten times the canine dose of 0.01 mg/kg. Using the dog dose will produce false negatives in cats. The pattern of suppression at 4 hours vs. 8 hours can also help differentiate pituitary-dependent from adrenal-dependent HAC.
ACTH stimulation test — limited role in cats
Synthetic ACTH is given and cortisol response measured. In dogs this has ~80–85% sensitivity for Cushing's; in cats sensitivity is only ~50%, making it a poor screening or confirmatory test for diagnosis. It remains useful for monitoring cats already on trilostane treatment — to confirm adequate cortisol suppression without over-suppression.
Abdominal ultrasound — adrenal assessment
Imaging of the adrenal glands is essential once HAC is biochemically confirmed. In pituitary-dependent HAC, both adrenals are enlarged symmetrically from chronic ACTH over-stimulation. In adrenal-dependent HAC, one adrenal contains a mass (adenoma or carcinoma) and the other is atrophied from suppressed ACTH. Adrenal carcinomas may show invasion into surrounding tissue or evidence of metastasis.
MRI or CT — pituitary imaging
If neurological signs are present, or if the clinical picture is consistent with pituitary-dependent HAC, brain MRI is recommended to characterize the pituitary tumor. A pituitary macroadenoma (large tumor) that is causing neurological signs changes the treatment approach — these cats benefit most from radiation therapy rather than or in addition to medical management.
Treatment of Cushing's Disease in Cats
Trilostane (Vetoryl) — first-line medical treatment
Trilostane inhibits an enzyme (3β-hydroxysteroid dehydrogenase) required for cortisol synthesis in the adrenal glands. It is the most widely used treatment for pituitary-dependent HAC in cats. It does not destroy adrenal tissue — it blocks cortisol production, so cortisol can be managed precisely by adjusting the dose. Cats are typically started on a low dose once daily, with monitoring using the ACTH stimulation test at 10–14 days after starting treatment, and at 4–6 weeks, and then every 3–6 months once stable.
- •Clinical improvement in skin fragility and coat quality may be seen within weeks
- •Concurrent diabetes often improves significantly — insulin doses frequently need to be reduced, sometimes substantially, to avoid hypoglycemia
- •Side effects include over-suppression (hypoadrenocorticism/Addisonian crisis) — lethargy, weakness, vomiting, collapse; seek emergency care if this occurs
Metyrapone — alternative medical option
Metyrapone also blocks cortisol synthesis and can be used when trilostane is unavailable, not tolerated, or insufficiently effective. It is given orally 2–3 times daily. It may be combined with other agents in refractory cases. Less widely available than trilostane in many regions.
Adrenalectomy — for adrenal-dependent HAC
Surgical removal of the affected adrenal gland can be curative for adrenal tumors. However, adrenalectomy in cats carries significant risk: skin fragility makes wound dehiscence common, anesthesia and surgical stress can trigger hemodynamic instability, and the remaining adrenal gland (which has been suppressed) needs time to recover. Perioperative glucocorticoid and mineralocorticoid supplementation is essential. Surgery is most appropriate when the tumor appears benign on imaging and has not metastasized, and when the cat's overall condition allows anesthesia.
Radiation therapy — for pituitary macroadenomas
Cats with large pituitary tumors causing neurological signs are candidates for radiation therapy, which can shrink the tumor and relieve mass effect. Radiation does not immediately lower cortisol — medical management continues alongside it. Specialized referral to a veterinary radiation oncology center is required. Stereotactic radiation (SRS/SRT) is preferred where available due to high precision and fewer treatment sessions.
Concurrent diabetes management
Managing the diabetes alongside the Cushing's requires careful coordination. As cortisol falls with treatment, insulin sensitivity improves — sometimes rapidly. Insulin doses that were appropriate before trilostane can quickly become excessive, causing dangerous hypoglycemia. Blood glucose monitoring (at home or via a continuous glucose monitor such as FreeStyle Libre) is especially important in the early weeks of treatment. Some cats achieve diabetic remission once the cortisol excess is controlled.
Watch for Hypoglycemia as Cortisol Falls
Managing Skin Fragility
Skin fragility syndrome requires specific care before and during treatment. The practical implications are significant:
- •Minimize scruffing: Use towel wrapping or other restraint methods that avoid putting tension on the skin. Alert all handlers — including boarding facilities and groomers — that the skin is fragile.
- •Venipuncture sites: Prefer leg veins (cephalic, saphenous) over jugular draws where tension on the scruff is unavoidable. Use the smallest gauge needle appropriate.
- •Wound care: Any skin tear needs prompt, careful attention. Wounds in Cushingoid cats heal slowly and can dehisce easily. Surgical closure is challenging — sutures may not hold. Keep wounds clean and covered; use non-adhesive dressings where possible.
- •Indoor-only: Cats with skin fragility should be kept strictly indoors to prevent trauma from outdoor hazards.
- •Improvement timeline: Skin integrity improves as cortisol falls with successful treatment, but recovery is slow — it may take weeks to months for collagen quality to meaningfully improve.
Prognosis
Prognosis for feline Cushing's is more guarded than for the canine disease, for several reasons:
| Scenario | Prognosis |
|---|---|
| Pituitary-dependent HAC, responds to trilostane | Fair to good — median survival ~1–2 years from diagnosis; good quality of life achievable |
| Concurrent DM that achieves remission with cortisol control | Improved — remission from insulin is a meaningful quality-of-life win |
| Pituitary macroadenoma with neurological signs | Guarded — neurological deterioration can occur; radiation therapy may extend survival |
| Adrenal adenoma, successful adrenalectomy | Good if surgery successful; curative potential with benign tumors |
| Adrenal carcinoma | Guarded to poor — higher rate of malignancy in cats; invasion and metastasis reduce outlook |
Related Reading
Cushing's Disease in Dogs
The canine version — classic high ALP, pot belly, hair loss, and what trilostane treatment involves.
Cat Diabetes: Blood Sugar Levels, Monitoring & Management
Insulin, glucose curves, and what stable diabetic management looks like in cats.
Acromegaly in Cats
Another pituitary-driven cause of insulin-resistant diabetes in cats — GH excess rather than ACTH.
Cat Hyperthyroidism: Symptoms & Blood Tests
The most common endocrine disease in older cats — also causes PU/PD and weight loss.
Cat Liver Enzymes Explained
What ALT, ALP, AST, and GGT mean in cats — and why the cat ALP isoform differs from dogs.
Pet Insurance for Cats With Cushing's Disease
Feline Cushing's requires specialist diagnosis (hormone testing, abdominal ultrasound, often MRI), ongoing trilostane medication, and frequent monitoring visits. Concurrent diabetes adds insulin, monitoring supplies, and glucose check costs. Pet insurance can significantly offset lifetime management expenses.
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Frequently Asked Questions
What is Cushing's disease in cats?
Cushing's disease (hyperadrenocorticism) is a condition of excess cortisol production. About 80–85% of cases in cats are caused by a pituitary tumor that over-secretes ACTH, driving both adrenal glands to produce too much cortisol. About 15–20% are caused by a cortisol-secreting adrenal tumor. Cushing's is much rarer in cats than in dogs and presents differently — most notably with fragile skin and concurrent insulin-resistant diabetes mellitus.
What are the signs of Cushing's disease in cats?
The most distinctive sign is skin fragility syndrome — skin that tears with minimal handling, poor wound healing, and papery texture. Most cats also have concurrent diabetes mellitus (often insulin-resistant), a pot belly, symmetrical hair loss along the trunk, muscle wasting, and recurrent infections. Neurological signs (circling, seizures, behavior change) can occur if there is a large pituitary tumor.
Why doesn't high ALP mean Cushing's in cats the way it does in dogs?
In dogs, excess cortisol induces a specific liver isoform of ALP (corticosteroid-induced ALP or C-ALP), which can cause ALP to rise 5–10 times above normal and serves as a reliable screening clue. Cats lack this isoform entirely. A cat with Cushing's can have a completely normal ALP. Veterinarians cannot use ALP to screen for or rule out Cushing's in cats — dedicated hormone tests are required.
How is Cushing's disease diagnosed in cats?
A urine cortisol:creatinine ratio (collected at home to avoid stress artifacts) is a useful initial screen. The low-dose dexamethasone suppression test (LDDS) is the preferred confirmatory test — at 0.1 mg/kg (ten times the canine dose). Abdominal ultrasound assesses adrenal gland size and looks for adrenal tumors. Brain MRI is used if neurological signs suggest a pituitary macroadenoma.
Will treating Cushing's help my cat's diabetes?
Often significantly, yes. Cortisol is a powerful anti-insulin hormone — it blocks insulin action and drives glucose production. Once cortisol is controlled with trilostane, insulin sensitivity commonly improves substantially. Insulin requirements often drop, sometimes dramatically, within weeks of starting treatment. Some cats achieve complete diabetic remission once cortisol is normalized. This is one of the most important reasons to diagnose and treat Cushing's in a diabetic cat.
What is the prognosis for a cat with Cushing's disease?
More guarded than for dogs — mainly because skin fragility complicates any surgery or procedure, adrenal carcinomas are more common in cats, and concurrent diabetes adds management complexity. Cats with pituitary-dependent HAC that respond well to trilostane can achieve median survival of 1–2 years with good quality of life. Some cats that achieve diabetic remission and have small, stable tumors do even better.
Want to understand your cat's bloodwork or diabetes results in context?
Upload your cat's chemistry panel, urinalysis, hormone test, or glucose curve — VetLens explains every value in plain language, flags what's out of range, and helps you track changes over time.
Upload My Cat's Results